The William Holman Hunt oil painting, purchased by the museum in 1947, is one of as many as four works the museum will sell over the next several months to pay off construction debt and replenish its endowment. The Delaware museum boasts the most significant collection of Pre-Raphaelite works outside of the United Kingdom.

Museum officials have declined to release the names of the other works, explaining that it could hurt the market for private sales. They have promised not to sell any works acquired through gift or bequest. Winslow Homer's "Milking Time," one of the museum's most treasured works, purchased in 1967, disappeared from its wall and collections database last month. Museum officials won't confirm that it is scheduled to be sold.

The museum's board voted to sell the art by October to meet a deadline to repay $19.8 million in debt from a 2005 facilities expansion. After exhausting fundraising efforts, officials said the museum was in danger of shutting down.

The only alternative, according to museum CEO Mike Miller, was for the museum to take out a short-term, high-interest bank loan to repay the debt. Rejecting that option, the board hopes to raise a total of $30 million from the sales, funneling the rest into the museum's $25 million investment reserve to ensure long-term stability.

Selling art to pay for operating expenses violates the professional standards of two major museum associations, the Association of Art Museum Directors and the American Alliance of Museums. The move drew swift criticism from association leaders, and could result in sanctions and loss of accreditation for the Delaware museum.

Mark Samuels Lasner, a senior research fellow at the University of Delaware Library and an expert on Victorian literature and art, described the impending Hunt sale as "sacrilege."

"Isabella and the Pot of Basil" is "an extraordinarily significant painting," said Lasner, who has amassed a 9,000-piece collection of Victorian books, manuscripts and letters that has been exhibited worldwide.

In 2009, Lasner helped organize the "Useful and Beautiful" international conference and related exhibitions, which highlighted Delaware's Pre-Raphaelite treasures. For the last 10 years, he has helped fund an annual Pre-Raphaelite student fellowship under a joint program between UD Library and the museum.

But Lasner said he is weighing no longer supporting the museum ‚?? either through fellowship funding or a financial bequest ‚?? in light of the Hunt sale.

In an email Tuesday to Miller, he suggested that the museum instead dispose of its post-1950 contemporary art holdings, "most of which are undistinguished."

The Pre-Raphaelite collection is the museum's "core, the reason for the institution's very existence," along with American illustration, Lasner wrote.

In an interview, Miller said the Hunt painting "is no more important than any others," and was selected because of its limited impact on the overall collection.

"We'd have as many people outraged by the contemporary works," he added.

This week, the museum has invited about 400 donors to participate in Q&A sessions about the sale with Miller and museum trustees.

The bulk of the museum's collection of more than 150 Pre-Raphaelite paintings, drawings, photographs and decorative arts was donated in 1935 by the descendants of Samuel Bancroft, a textile mill owner in Wilmington.

Bancroft's family also donated the land in Wilmington where the museum now sits.

Hunt, one of the original seven founders of the Pre-Raphaelite Brotherhood along with Dante Gabriel Rossetti, represented a hole in the Bancroft collection. His painting was acquired by the museum in 1947 using general acquisition funds. As of Tuesday, it was still highlighted among 10 Pre-Raphaelite paintings on the museum's Bancroft collection website, www.preraph.org.

Completed in 1868, "Isabella and the Pot of Basil" depicts a scene from the John Keats poem of the same name. The heroine Isabella drapes herself over a basil pot altar in which she has buried the head of her lover, Lorenzo, who was murdered at the hands of her brothers. She waters the tomb with her tears.

Hunt's wife, Fanny, served as a model for Isabella. She died during childbirth two years before the painting was finished. Art historians believe Isabella's mourning for Lorenzo may reflect Hunt's own grieving process.

The museum owns three other minor Hunt works ‚?? a drypoint on paper, an etching and engraving ‚?? that are not on display.

Admired for his attention to detail and vivid colors, the painter produced two versions of "Isabella." A similar work, owned by the Laing Art Gallery in Newcastle, England, was displayed in 2012 and 2013 at Tate Britain for a Pre-Raphaelite exhibition. The Delaware museum contributed three works to that show.

The price that "Isabella" will fetch is unclear. The museum previously shopped the painting to private buyers, but determined that it would command a higher price at auction, Miller said.